Author: Chris Nelson

Freedombot is a neat little robot designed for exploring magnetic surfaces. It has two whiskers for detecting objects in its path and two rare earth magnets which allow it to stick to your fridge.

Overall Freedombot may not be anything revolutionary but its builder [skater_j10] does a good job of covering topics which my be interesting to robotics beginners. For example he goes through the process of modifying some HiTec HS- 55 Micro Servos for continuous rotation which allows them to act as the wheels. To control the bot he uses two 555 timers wired up in astable mode to generate the needed PWM for the servos. The proximity sensors are simple limit switches with some wire soldered on to the end. The end result is a neat little robot for roaming the front of your fridge. See a video of it in action after the break.

This happens to be [skater_j10]’s entry into the 555 timer contest. Unfortunately the deadline has passed for new entries but be sure to swing by and check out some more awesome 555 hacking.

The original PSP may be old news but there is an interesting relic of a website (translated) dedicated to the reverse engineering of a PSP (and exploring Saturn?). To determine the true capabilities of the PSP they desoldered most of the ball grid array chips and then hand soldered 157 jumper wires to allow for direct memory access. In later pictures it shows the PSP hooked up to external hardware for on the fly memory modification. Unfortunately the details are sparse and it doesn’t appear as if they will be updated anytime soon because the website has been “deleted and freezed because of spam. may ineffaceable curse prevail on the spammers.” Still this doesn’t detract too much some very impressive soldering.

The Nintendo 3DS has been out for a couple days now (in japan) and the folks over at [tech on] were nice enough to do a teardown. Besides all the regular teardown goodies you can also get a good look at the 3DS’ 3D screen with a microscope. Turns out its a parallax barrier display which means that there are slits on top of the LED array to create a 3D effect without the use of special glasses. The rest of the hardware seems pretty standard, running an ARM based processor with some DRAM and NAND flash. Apparently the 3DS didn’t get much of an upgrade (downgrade?) as far as DRM is concerned because there are already examples of the 3DS running pirated games using a R4 card on youtube.

Halloween may have come and gone but thats no reason not to take a look at this neat little special effects setup. Basically it uses an analogue circuit to monitor an audio signal and triggers some camera flashes using 5V relays. The idea is that you can play lightning strikes and other spooky sounds, and the system will trigger camera flashes to coincide with the lightning strikes. Adding in some color organs in addition to the camera flashes will dim your lights to help achieve a thunder like effect. Unfortunately there aren’t any schematics for the color organs (which technically might be just light organs) but that doesn’t detract from the seemingly well designed analogue signal processing. Check it out in action after the break.

[Alexander Avtanski] has put together a nice clock to meet all your interstellar travel needs. Besides being another PIC based timer, this is a neat little project because it incorporates pretty much every feature you could think of when building a clock for our solar sytem. For example, it has 16 independent timers and alarms, it can simultaneously give the time for multiple planets, as well as keep track of other stellar events like the eye of Jupiter or the phases of the moon. To get this project off the ground [Alex] reverse engineered an old dial up modem to serve as an enclosure and power supply and then added in a rechargeable battery so that his his interstellar clock wasn’t tied to a wall.

[Embedded lab] has a nice tutorial on building your own heart rate monitor. The monitor works by shining infrared light into the fingertip and looking at the changes in the reflected infrared signal caused by a heartbeat. The IR detector produces a very small AC signal so a couple of op-amps are used to filter and amplify the signal. The output of the filter circuit is then read in by a PIC16F628A, which counts the beats and displays it on a seven segment display. This might be a good project to try if you’ve got your microcontrollers down and you are looking to learn some analog electronics. Its noted at the end that the two main problems with building a circuit like this are going to be cross talk and adjusting the filters. The infrared diode and receiver should be close to each other to allow maximum reflection but you also need to make sure that you don’t allow the emitter to shine directly into the detector because the reflected light will be drowned out by the bright emitter.

The researchers at Brookhaven National Laboratory are looking for a way to harden photomultiplier tubes. In order to make a more durable tube the researchers decided it would be a good idea to first observe how the tubes are failing. So they got their hands on an old torpedo test bay and smashed some bulbs inside of it. Check in after the break for some high fps bulb smashing.

Photomultiplier tubes are used in massive quantities to detect the highly elusive neutrino particle. The problem is when you have 50,000 photomultipliers submerged in pressurized water the the collapse of just a single bulb can cause a shock wave of destruction. This is what happened in japan in 2001 when a maintenance worker unknowingly compromised a single bulb in a 11,000 bulb array. When the tank was repressurized that single compromised bulb caused them to lose 7,000 more.